Converting from Option to Option

by

As of Rust 1.40, the standard library has Option::as_deref to do this:

fn main() {
    let opt: Option<String> = Some("some value".to_owned());
    let value = opt.as_deref().unwrap_or("default string");
}

See also:

More Related Contents:

  1. Why can’t I store a value and a reference to that value in the same struct?
  2. The compiler suggests I add a ‘static lifetime because the parameter type may not live long enough, but I don’t think that’s what I want
  3. How do I stop iteration and return an error when Iterator::map returns a Result::Err?
  4. Are polymorphic variables allowed?
  5. Why does Iterator::take_while take ownership of the iterator?
  6. When should I implement std::convert::From vs std::convert::Into?
  7. Sending trait objects between threads in Rust
  8. Why would I implement methods on a trait instead of as part of the trait?
  9. How to initialize struct fields which reference each other
  10. “Expected fn item, found a different fn item” when working with function pointers
  11. How do you unwrap a Result on Ok or return from the function on Err?
  12. How do I read the entire body of a Tokio-based Hyper request?
  13. How can I downcast from Box to a trait object type?
  14. When returning the outcome of consuming a StdinLock, why was the borrow to stdin retained?
  15. How does Rust pattern matching determine if the bound variable will be a reference or a value?
  16. What is a crate attribute and where do I add it?
  17. Parameter type may not live long enough?
  18. Why does Rust disallow mutable aliasing?
  19. How to store rusqlite Connection and Statement objects in the same struct in Rust? [duplicate]
  20. How to model complex recursive data structures (graphs)?
  21. print! macro not executed until pressing Enter
  22. How can I define an async method in a trait?
  23. How do I specify the linker path in Rust?
  24. Why am I getting “parameter is never used [E0392]”?
  25. How do I specify that a struct field must implement a trait?
  26. What does Rust’s unary || (parallel pipe) mean?
  27. How to create and write to memory mapped files?
  28. Downcast traits inside Rc for AST manipulation
  29. How to check in Rust if architecture is 32 or 64 bit?
  30. Is there any way to restrict a generic type to one of several types?

Leave a Comment